Semi-automatic gearshift transmissions designed as group transmissions with a multi-step main transmission and a downstream group, in particular designed as a range group in drive connection downstream from the main transmission, and/or an upstream group, in particular designed as a splitter group in drive connection upstream from the main transmission, are known for example from DE 10 2007 010 829 A1, and are used for example in commercial vehicles. By means of a splitter group for example designed with two steps with a gear ratio interval that corresponds to approximately half of an average gear ratio interval between two consecutive gear ratio steps of the main transmission, the gear ratio intervals of the main transmission are halved and the total number of gears available is doubled. By means of a range group, for example with two steps with a gear ratio interval above the total gear ratio interval of the main transmission by approximately an average gear ratio interval between two consecutive gear ratios of the main transmission, the spread of the group transmission is approximately doubled and the total number of gears available is again doubled.